Most external batteries can charge up your phone or your tablet, but you’re out of luck with your laptop. The BatteryBox is only 0.98″ x 2.63″ x 3.55″ and just under 9 ounces, but it packs 50Wh of energy – enough juice to power your MacBook with enough left over to charge your mobile device, too. You can double the battery life of a MacBook Air or charge 8 iPhones with a single charge on the BatteryBox. It doesn’t recharge the MacBook’s battery. Instead, it bypasses the internal battery and supplies power directly to the MacBook; this minimizes the number of recharge cycles on the laptop’s battery and extends its life. The BatteryBox is powered by “BatteryOS, a new way of controlling rechargeable lithium-ion batteries that enables them to have higher capacity and not degrade over time. That means BatteryBox will last 3000 full charge and discharge cycles, and still retain 96% of capacity after 5 years.” It will work with any Macbook with MagSafe2 and can charge any device charged by USB.

The BatteryBox will ship in Fall 2014; a $10 deposit will reserve one. You’ll be charged $129 when the BatteryBox is ready to ship to you.